South Korea’s resident registration numbers were the country’s biggest target of data theft over the past three years, a local report said Wednesday.

According to the report by Rep. Lee Jasmine of the ruling Saenuri Party, nearly 130,000 cases in which ID numbers had been misused or stolen were reported to the state-run Korea Internet and Security Agency between 2011 and 2013.

The figure accounted for 73 percent of all private information breaches reported in the same period, she said, adding that the report was written with data submitted by the KISA.

The 13-digit resident registration number, which is assigned to every Korean at their birth, contains basic personal information such as gender and date and place of birth. The ID numbers are widely used in financial affairs, from tax and property registration to medical insurance and military services. People have to submit the number when opening bank accounts or applying for credit cards.

“We still have a large number of people reporting their ID numbers being stolen and illegally used,” a KISA official said. “But we expect that the number will fall in the second half of the year as new law that bans collection of ID numbers, goes into effect in August.”

Starting Aug. 7, both public agencies and private companies will be prohibited from collecting or processing resident numbers unless they are warranted under legal requirements.

The government’s new measures came after the country was hit by a massive leak of client databases at Lotte Card, KB Kookmin Card Co., and NongHyup Card. An employee of the Korea Credit Bureau stole the personal data of up to 20 million clients at card companies in June last year.

The leak, belatedly made public in June this year, sparked concerns over the risk of personal information protection.

Lee called for additional countermeasures to prevent privacy invasion, saying that the risk of ID numbers being exposed remains high.